1. Field of the Invention
The present invention relates to a highly sensitive light reception element capable of converting variation in quantity of light into an electrical signal with high response speed.
2. Description of the Related Art
Conventionally, a light reception element that exhibits differential responsiveness has been developed in the form of an electrochemical cell having a layered structure of transparent electrode/bacteriorhodpsin thin film/electrolyte/counter electrode (see Japanese Patent Application Laid-Open No. 3-205520 and Miyasaka, Koyama, and Itoh, Science 255, 342, 1992).
Such a light reception element is known as a first element that exhibits differential responsiveness in the level of the material thereof. Although the light reception element has various advantages, its extremely low sensitivity is its weakest point.
Further, there is anxiety about the reliability of the light reception element, because the light reception element utilizes a protein as a basic material.
FIG. 1 shows a response pattern of the conventional light reception element (which will be described later for comparison with the present invention in terms of effect).